The present invention relates in general to emergency locking retractors and means for reducing the tension applied to the safety belt due to the retractor rewind spring when the belt is placed in use. More specifically, the present invention relates to a dual tension single spring retraction means for an emergency locking retractor which provides for a reduced tension on the safety belt when the belt is placed in use as compared to a higher tension applied by the retractor spring to the belt durng normal protraction and retraction.
Various types of emergency and automatic locking retractors have been employed heretofore for restraining passengers in their seats in vehicles such as automobiles. Some passengers find the tension applied to the safety belt, particularly the chest strap of a safety belt harness system, due to the retractor rewind spring objectionable when the belt is placed in use. In order to overcome such undesirable belt tension, various means have been developed heretofore for reducing the tension of the safety belt retractor spring upon the safety belt when the belt is placed in use. An example of one such prior effort is U.S. Pat. No. 3,834,646 wherein the rewind bias of the retractor spring is entirely blocked upon a predetermined manipulation of the protracted belt. Other approaches, as that of U.S. patent application Ser. No. 769,682 filed Feb. 17, 1977 which is a continuation of U.S. patent application Ser. No. 627,875 filed Oct. 31, 1975, now abandoned, in the name of Charles Ulrich and assigned to the assignee of the present application improve upon the prior patent in providing for a lower tension belt rewinding bias while the main biasing effect of the rewind spring is blocked out so that a loose belt condition is avoided and the belt will be retracted under the low tension bias for a limited extent of travel and then rewound under full bias of the retractor spring without the need for a protraction of the belt to release the tension relieving means as in the foregoing patent.
I have heretofore recognized that it would be desirable to provide a dual tension retraction mechanism for a safety belt retractor utilizing a single retractor spring and having gear means for transmitting the spring force to the reel and selectively operating the gear means in a force transmitting mode.